package com.xiaoma.chat.utils;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class GzipUtils {

    public static void doCompressFile(String inFileName) {

        try {

            System.out.println("Creating the GZIP output stream.");
            String outFileName = inFileName + ".gz";
            GZIPOutputStream out = null;
            try {
                out = new GZIPOutputStream(new FileOutputStream(outFileName));
            } catch (FileNotFoundException e) {
                System.err.println("Could not create file: " + outFileName);
                System.exit(1);
            }

            System.out.println("Opening the input file.");
            FileInputStream in = null;
            try {
                in = new FileInputStream(inFileName);
            } catch (FileNotFoundException e) {
                System.err.println("File not found. " + inFileName);
                System.exit(1);
            }

            System.out.println("Transfering bytes from input file to GZIP Format.");
            byte[] buf = new byte[1024];
            int len;
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
            in.close();

            System.out.println("Completing the GZIP file");
            out.finish();
            out.close();

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }

    }

    public static void doUncompressFile(String inFileName) {

        try {

            if (!getExtension(inFileName).equalsIgnoreCase("gz")) {
                System.err.println("File name must have extension of \".gz\"");
                System.exit(1);
            }

            System.out.println("Opening the compressed file.");
            GZIPInputStream in = null;
            try {
                in = new GZIPInputStream(new FileInputStream(inFileName));
            } catch (FileNotFoundException e) {
                System.err.println("File not found. " + inFileName);
                System.exit(1);
            }

            System.out.println("Open the output file.");
            String outFileName = getFileName(inFileName);
            FileOutputStream out = null;
            try {
                out = new FileOutputStream(outFileName);
            } catch (FileNotFoundException e) {
                System.err.println("Could not write to file. " + outFileName);
                System.exit(1);
            }

            System.out.println("Transfering bytes from compressed file to the output file.");
            byte[] buf = new byte[1024];
            int len;
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }

            System.out.println("Closing the file and stream");
            in.close();
            out.close();

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }

    }

    /**
     * Used to extract and return the extension of a given file.
     * 
     * @param f
     *            Incoming file to get the extension of
     * @return <code>String</code> representing the extension of the incoming
     *         file.
     */
    public static String getExtension(String f) {
        String ext = "";
        int i = f.lastIndexOf('.');

        if (i > 0 && i < f.length() - 1) {
            ext = f.substring(i + 1);
        }
        return ext;
    }

    /**
     * Used to extract the filename without its extension.
     * 
     * @param f
     *            Incoming file to get the filename
     * @return <code>String</code> representing the filename without its
     *         extension.
     */
    public static String getFileName(String f) {
        String fname = "";
        int i = f.lastIndexOf('.');

        if (i > 0 && i < f.length() - 1) {
            fname = f.substring(0, i);
        }
        return fname;
    }

    /**
     * Sole entry point to the class and application.
     * 
     * @param args
     *            Array of String arguments.
     */
    public static void main(String[] args) {
//        String str = "/Users/houxiufeng/Desktop/gzip.json";
//
//        doCompressFile(str);
        doUncompressFile("/Users/houxiufeng/Desktop/ggzz/gzip.json.gz");
    }
}
